Preparation of arginine-glutaric acid-based-deep eutectic solvent and its application as a potent catalyst for the synthesis of pyranopyrimidines

A new natural deep eutectic solvent (DES) based on arginine (ARG) and glutaric acid (GLU) was prepared. The eutectic point phase diagram showed that the best ratio for preparation of ARG/GLU-DES is one mole of ARG to three moles of GLU. Then, the new DES was characterized by eutectic points, FT-IR, ¹H NMR, TGA/DTA, and densitometry techniques. Additionally, it was demonstrated to be an effective catalyst for the green synthesis of pyrano[2,3-d]-pyrimidines through a one-pot three-component condensation reaction of aromatic aldehydes, barbituric acid, and 4-hydroxycoumarin at 80 °C under solvent-free conditions with high yields and short reaction times.